Card Set Information
Contain finely divided solid (suspensoid) distributed giving minimum degree of solubility.
The dispersed phase is _____ where as the contiunous phase is _____.
Examples of dispersed phase are
T/F There is no such thing as an IV suspension
Advantages of oral suspensions
Easy to swallow and flexible dosing
Disadvantages of Oral suspensions
relative instability (vs solids)
Comminutions is what?
Particle size reduction
Process of making oral suspension
Solid drug is comminuted, wetted, then suspended.
Three important issues for suspensions
Goal for particle size
1-50 micrometers in diameter
3 industrial ways to reduce particle size
Micropulverization- 1-050 Micro meters
Jet milling- <10 micro meters
Other methods of particle reduction
Problems with particle wetting
Some problems are that the drug might be hydrophobic or there are air pockets
Suspension can be irreversibly altered by these 3 types of physical instability
Particle settling, aggregation, and growth.
Stokes equation, what do the variables stand for?
V- falling velocity
Ro1- density of sphere
ro2- density of liquid
n- viscosity of dispersion
Dispersion medium viscosity
As particle size decreases what increases?
Interfacial surface area and free energy
These are types of interparticulate forces
Electrostatic- (keeps particles apart)
Van der waal- (keeps them together)
Particles aggregate very strongly at _____ and weakly at ________.
Primary minimum (close distance)
Secondary minimum (far distance)
to drive together (strongly bound at primary minimum)
Combination of settling and coagulation makes a non-redispersable sediment.
Flocculated is usually at the _______ minimum
Secondary, loose and wooly. Easier to redisperse
Ostwald ripening is the growth of large particles at the expense of ______.
Ostwald ripening is accelerated by
Wetting agents help _____ the solids, Flocculating agents help keep them ____, and suspensing agents help keep the solids ______.
Types of wetting agents are
Surfactants, solvents, and certain polymers
examples of surfactants
Anionic- docusate sodium
Ionic- polysorbates (tweens)
Solvent examples are
Alcohol, glycerol, propylene glycol
Types of flocculating agents
Electrolytes, Surfactants, and Certain polymers
T/F Dissolution depends on viscosity and bioavailabilty depends on dissolution
For a newtonian liquid shear rate is _______. Viscosity is _______.
Linear function of shear stress
According to the graphs, as the line becomes more steeper it becomes _____ viscous.
For plastic liquids, minimum shear stress must be achieved for what to happen?
A thixotropic liquid will __ when aggitated but will form a ___ when standing still.
Hysteresis is when the restrictive network ______ reforms.
Xanthan gum is (ionic/anionic) and has ____ temperature stability, and a high _____.
Hydroxypropylmethylcellulose is a ______ polymer
Sodium carboxymethylcellulose is an _____ polymer
T/F Gums are not polysaccharides.
False, they ARE